Automatic reclosing circuit-breaker system



Oct. 22, 1929. A. E. ANDERSOS? 1,732,296

AUTOMATIORECLOSING CIRCUIT BREAKER SYSTEM Filed June 2'7, 192'? Inventor I Ar vid E. Anderson,

His Attorney.

Patented Oct. 22, 1929 UNITED STATES PATENT OFFICE ARVID E. ANDERSON, OF SCO'IIA, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC C011 PANY, A CORPORATION OF NEW YORK AUTOMATIC RECLOSING CIRCUIT-BREAKER SYSTEM Application filed June 27, 1927. Serial No. 201,672.

- My invention relates to automatic reclosing c1rcu1t breaker systems and its ob ect is to provide an improved arrangement for effecting the reclosing of a circuit breaker between two electric circuits whenever either of the circuits is energized and the other circuit is free from short circuits and overloads. More particularly my invention relates to an improvement of the arrangement disclosed and claimed in my copending application Serial No. 733,918, filed August 25, 1924.

My invention will be better understood from the following description taken in con :nection with the accompanying drawing which shows an automatic reclosing circuit breaker system embodying my invention and its scope will be pointed out in the appended claims.

Referring to the drawing, 1 represents a circuit breaker which is arranged to connect together the conductors 2 and 3 of two elec-' tric circuits which are arranged to be energized independently of each other by sources not shown. In order to simplify the drawing, it has been assumed that the ground is the other side of both of the circuits, but it is obvious that myinvention is'not limited to a grounded system.

The circuit breaker 1, which may be of any suitable type, examples of which are well known in the art, may be arranged in any suitable manner so that it is opened upon the occurrence of predetermined abnormal conditions on either of the circuits 2 and 3. As shown in the drawing the circuit breaker is of the well known contactor type and is provided with a closing coil 4, the circuit of which is arranged to be opened by an overload relay 5 when the current flowing through the circuit breaker, when it is closed, exceeds a predetermined value. 6 is a load indicating resistor which is arranged to be connected in series between the'circuits 2 and 3 when'the circuit breaker l is open. This current limiting device permits a current to fiow from one circuit to the other when the circuit breaker is open. This current varies/in magnitude in accordance with the voltage'diiference between the two circuits. The current through the resistor 6 therefore is an indication of the and the load conditions on the other circuit are such that the circuit breaker will not open immediately when it is reclosed. For accomplishing this result I provide a reclosing relay 7 which is rendered operative after the circuit breaker has been open a predetermined length of time to effect the reclosing of the circuit breaker l whenever either circuit is energized at substantially normal voltage and the load connected to the other circuit is less than a predetermined value.

As shown in the drawing the reclosing relay 7 comprises two electromagnets 8 and 9 which are arranged to exert opposing forces on a movable member 10. The electromagnet 8 comprises an actuating winding 11 and a holding winding 12 which when energized tend to close and maintain closed the contacts 13 of the relay 7. The electromagnet 9 comprises a restraining winding 14 which when energized tends to open the contacts 13. The electromagnet 9 also comprises a compensatingwinding 15 which is connected and arranged to compensate for the difference in the effect of the electromagnets 8 and 9 on the member 10 due to the change in the direction of the current through one of the windings. This particular arrangement for compensating for the difference in the action of the relay arising from a change in the direction of the current through one of its windings is disclosed and claimed in a copending application of F. H. Winter Serial No. 160,729, filed J anuary 12, 1927.

In the particular arrangement shown in the drawing the restraining winding 14 is connected in parallel with the resistor 6 so that it is energized in accordance with the cur rent flowing through the resistor. It will be observed, therefore, that the direction of the current through the winding depends upon which circuit has the higher voltage. The winding 15, which is arranged to compensate for the difference in the action of the relay due to this reversal of current through the- Winding 14, and the actuating winding 11, are arranged to be connected to whichever circuit is energized when only one circuit is energized, and from the circuit 2 when both of the circuits 2 and 3 are energized. In order to connect the windings 11 and 15 across whichever circuit is energized when only one is energized and across circuit 2 when both of the circuits 2 and 3 are energized, I provide a control relay 16 which is arranged to be connected across the'circuit 2 when the cir cuit breaker 1 is open. This control relay 16 selectively controls the circuits of the windings 11 and 15 so that when the circuit breaker is open and the'control relay 16 is deenergized the windings 11 and 15 are connected across circuit 3 and when the control In order to prevent the relay 7 from effecting the reclosing of the circuit breaker 1 before a predetermined time has elapsed after its opening I provide suitable means for maintaining the circuits of the windings 11 and 15 open until after the circuit breaker has been open a predetermined length of time. This result is accomplished in'the arrangement shown in the drawing by providing the circuit breaker 1 with auxiliary'contacts'17 and 18 which are connected in the circuits of the windings '11 and 15 and in the circuit of the winding of the relay 16 respectively. These auxiliary contacts 17 and 18 are arranged in any suitable manner, examples of 'which are well known in the art, so that they auxiliary contacts 20 on the circuit breaker do not close until after the circuit breaker has been open a certain..length of time. As shown in the drawing the closing of contacts 17 and 18 when the'circuit breaker opens is retarded b'ya dash pot 19.

The operation of the arrangement shown in the drawing is as follows: When the circuit breaker 1 is closed a circuit is completed for the closing coil 4 from conductor 3 through 1, conductor 21, contacts 22 of overload relay- 5, closing coil 4 to ground.

lVhen an overload or short circuit occurs load relay 5 opens itscontacts 22 and thereby opensthe above traced circuit for the closing coil 4 so that the circuit breaker 1 opens and the resistor 6 is inserted in series with the conductors 2 and 3. The resistance of the resistor is high relative to the normal load resistance so thatsubstantially normal voltage is impressed across the restraining winding 14 of the relay 7 as soon as the circuit breaker opens. Since the actuating winding 11 is not energized at this time, the energization of the winding 9 insures that relay 7 is moved to its open position prior to the time the relay is rendered operative to effect the reclosing of the circuit breaker.

The opening of the circuit breaker 1 effects the closing of the auxiliary contacts 17 and 18 after a predetermined time. The closing of the contacts 18 connects the control relay 16 across the circuit 2 so that if the circuit 2 is energized at substantially normal voltage relay 16 operates to open its contacts 23 and close its contacts 24.

It will be assumed that circuit 2 is energized at substantially normal voltage and that an abnormal load causes the circuit breaker 1 to open and remain connected across circuit 3 after the circuit breaker 1 is opened. The relay 16 therefore by closing its contacts 24 connects the windings 11 and 15 of the relay 7 across the energized circuit 2. The circuit for windings 11 and 15 is from conductor 2, through contacts 24 of relay r16, resistor 25, conductor 26, auxiliary contacts 17 on the circuit breaker 1, conductor 27, windings 15 and 11 of relay 7 in seriesto ground. The actuating winding 11 therefore is energized in accordance with the voltage of the energized circuit 2. designed however so that it'does not close its contacts 13 until the torque exerted by the winding 11 exceeds the torque exerted by windings 14 and 15a certain amount..,

Preferably the relay is designed so that it operates in response to a predetermined ratio between the supply circuit voltage and the voltage drop across the resistor 6.

As long as the fault remains connected across the circuit 3 the voltage drop across the resistor 6 is such that the torque exerted by win-dingll does not exceed the torque exerted by the winding 14sufiiciently to cause the relay to'close its contacts 13. 'As the resistance of the fault increases less current flows through the resistor6 so that the torque exerted by the winding 14 decreases. When the load resistance of circuit 3 increases to such a value that the torque exerted by winding 11 exceeds the torque exerted by the winding 14 sufliciently to cause the relay-7 to close its contacts 13, a circuit is completed for the closing coil 4 to close the circuit breaker 1. This circuit is from conductor 2 through contacts 24 of control relav. 16, resistor 25, Conductor 26, contacts 13 of relay 7, holding winding 12 of relay 7,'conductor 21, contacts 22 of overload relay 5, closing coil 4 to ground. Holding windin 12 exerts an additional torque to maintaln the contacts 13 closed and therebyinsures that the contacts- 13 remain closed long enough to permit the circuit breaker to complete its closlng operation.

The circuit breaker 1, by closing its auxiliary contacts 20, completes the heretofore described locking circuit for the closing coil 4. The circuit breaker 1, by closing its main contacts, short circuits the wind- The relay 7 is circuits to the windings 11. and 15. Preferably the relay 16 isarranged so that it does not immediately open its contacts after the circuit thereof is opened by the contacts 18. In the arrangement shown in the drawing this result is obtained by the discharge resistor 29 which is connected in shunt around the coil of the relay 16. Therefore the circuit for the closing coil 4 which is completed through contacts 13 and holding coil 12 of relay 7 is maintained closed for a suflicient time after the circuit breaker 1 is closedtopermittheheretofore described locking circuit for the holding coil 4 through auxiliary contacts 20 to be completed before the circuit through the contacts 13 and holding coil 12 is-opened. Since auxiliary contacts 2O short circuit the holding coil 12 of relay 7, this relay is restored to its normal position by the biasing spring 28.

If the circuit 3 is energized and the fault is across the circuit 2 after the circuit breaker 1 opens the operation is the same as above described except that relay 16 is not energized and therefore conductor 26 is connected to the conductor 3 by the contacts 23 of relay 16 so that the windings 11 and 15 of the reclosing relay 7 and closing coil 4 are energized from the circuit 3 which in this case is the supply circuit. I

In order to limit the current through the contacts 23 and 24 of the relay 16 in case these contacts momentarily overlap so that they connect the conductors; 2 and 3 together I provide the resistor 25 Which is connected in such a manner that it is in series between as applied to a particular system and as'em-- bodying various devices diagrammatically indicated, changes and modifications will be obvious to those skilled in the art, and I, therefore, aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invent-ion, r

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In an automatic reclosing circuit breaker system, two electric circuits, a circuit breaker for connecting said circuits together, electroresponsive means for effecting the closing of said circuit breaker including a winding, two

, circuits forsaid winding, and a voltage relay responsive to the voltage of one of said electric circuits each time the circuit breaker is open for selectively controlling the circuits of said winding.

2. In an automatic reclosing circuit breaker system, two electric circuits, a circuit breaker for connecting said circuits together,

electroresponsive means for effecting the closing of said circuit breaker including a winding, two circuits for said winding, a-relay responsive to the voltage of one of said circuits each time the circuit breaker is open, contacts in one of the circuits of said winding arranged to be closed by said relay when the voltage of said one of said circuits is above a predetermined value, and other contacts in the other circuit of said winding arranged to be closed by said' relay when the voltage of said one of said circuits is below a predetermined value.

3. In an automatic reclosing circuit breaker system, two electric circuits, a circuit breaker for connecting said circuits together, electroresponsive means for effecting the closing of said circuit breaker including a winding, a circuit for said winding adapted to be com-' pleted across one of said electric circuits, another circuit for said Winding adapted to be completed across theother electric circuit, overload means for effecting the opening of said. circuit breaker, a control relay having an operating-coil, means responsive to the opening of said circuit breaker for connecting the operating coil of said relay across a certain one of said electric circuits each time the circuit breaker is opened, contacts in one of the circuits of said winding arranged to be closed by said control relay when the volt-age ofsaid one of said electric circuits is above a predetermined value, and contacts in the other circuit of said winding arranged to be closed by said relay when the voltage of said one of'said electric circuits is below a predetermined value.

4. In an automatic reclosing circuit breaker system, two electric circuits, a circuit breaker for connecting. said circuits together, overload means for effecting the opening of said circuit breaker, a control relay responsive to the voltage of one ofsaid circuits each time the circuit breaker is opened, a reclosing relay including a voltage winding, a circuit for said voltage winding adapted to be connected across one of said electric circuits, another circuit for said voltage winding adapted tobe connected across the other electric circuit, contacts in one of the circuits of said voltage winding arranged to be closed by said control relay when said control relay is energized, and contacts in the other circuit of said voltage winding arranged to be closed by said control relay when said control relay is deenergized.

5. In an automatic reclosing circuit breaker system, two electric circuits, a circuit breaker for connecting said circuits together, a current limiting device arranged to be connected in series with said electric circuits when said circuit breaker is open, overload responsive means for effecting the opening of said circuit breaker, electroresponsive means for effecting the closing of said circuit breaker including a winding, acircuit for said Winding adapted to be connected to one point on said current limiting means, another circuit for said winding adapted to be connected to another point on said current limiting means,

a voltage relay connected across one of said electric circuits each time the circuit breaker is opened, contacts in one of the circuits of said winding arranged to be closed by said voltage relay when. it is energized a predetermined amount, contacts in the other circuit of said winding arranged to be closed by said Voltage relay when it is deenergized, and other contacts in each circuit of said winding arranged to be closed after said circuit breaker has been open a predetermined length of time.

6. In an automatic reclosing circuit breaker system, two electric circuits, a circuit breaker for connecting said circuits together, a current limiting device arranged to be connected in series'with said electric circuits when said circuit breaker is open, overload responsive means for effecting the opening of said circuit breaker, electroresponsive means for effecting the closing of said circuit breaker including a Winding, a circuit for said winding adapted to be connected to one point on said current limiting means, another circuit for said winding adapted to be connected to another point on said current limiting means, a voltage relay connected across one of said electric circuits each time the circuit breaker is opened, contacts in one of the circuits of said winding arranged to be closed by said voltage relay when it is energized a predetermined amount, and contacts in the other circuit of said winding arranged to be closed by said voltage relay when it is deenergized. In Witness whereof, I have hereunto set my hand this 25th day of June, 1927.

ARVID E. ANDERSON. 

